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ARM .align NOP padding uses different encoding pre-ARMv6. 

Patch by Kristof Beyls and James Malloy.

llvm-svn: 137723
This commit is contained in:
Jim Grosbach 2011-08-16 17:06:20 +00:00
parent be93a35a8a
commit 45e50d8a0b
5 changed files with 81 additions and 14 deletions
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51
llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
View File

@ -7,6 +7,7 @@
//
//===----------------------------------------------------------------------===//
#include "MCTargetDesc/ARMMCTargetDesc.h"
#include "MCTargetDesc/ARMBaseInfo.h"
#include "MCTargetDesc/ARMFixupKinds.h"
#include "MCTargetDesc/ARMAddressingModes.h"
@ -20,6 +21,7 @@
#include "llvm/MC/MCSectionELF.h"
#include "llvm/MC/MCSectionMachO.h"
#include "llvm/MC/MCAsmBackend.h"
#include "llvm/MC/MCSubtargetInfo.h"
#include "llvm/Object/MachOFormat.h"
#include "llvm/Support/ELF.h"
#include "llvm/Support/ErrorHandling.h"
@ -35,12 +37,23 @@ public:
};
class ARMAsmBackend : public MCAsmBackend {
const MCSubtargetInfo* STI;
bool isThumbMode; // Currently emitting Thumb code.
public:
ARMAsmBackend(const Target &T) : MCAsmBackend(), isThumbMode(false) {}
ARMAsmBackend(const Target &T, const StringRef TT)
: MCAsmBackend(), STI(ARM_MC::createARMMCSubtargetInfo(TT, "", "")),
isThumbMode(false) {}
~ARMAsmBackend() {
delete STI;
}
unsigned getNumFixupKinds() const { return ARM::NumTargetFixupKinds; }
bool hasNOP() const {
return (STI->getFeatureBits() & ARM::HasV6T2Ops) != 0;
}
const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const {
const static MCFixupKindInfo Infos[ARM::NumTargetFixupKinds] = {
// This table *must* be in the order that the fixup_* kinds are defined in
@ -122,20 +135,28 @@ void ARMAsmBackend::RelaxInstruction(const MCInst &Inst, MCInst &Res) const {
}
bool ARMAsmBackend::WriteNopData(uint64_t Count, MCObjectWriter *OW) const {
const uint16_t Thumb1_16bitNopEncoding = 0x46c0; // using MOV r8,r8
const uint16_t Thumb2_16bitNopEncoding = 0xbf00; // NOP
const uint32_t ARMv4_NopEncoding = 0xe1a0000; // using MOV r0,r0
const uint32_t ARMv6T2_NopEncoding = 0xe3207800; // NOP
if (isThumb()) {
// FIXME: 0xbf00 is the ARMv7 value. For v6 and before, we'll need to
// use 0x46c0 (which is a 'mov r8, r8' insn).
const uint16_t nopEncoding = hasNOP() ? Thumb2_16bitNopEncoding
: Thumb1_16bitNopEncoding;
uint64_t NumNops = Count / 2;
for (uint64_t i = 0; i != NumNops; ++i)
OW->Write16(0xbf00);
OW->Write16(nopEncoding);
if (Count & 1)
OW->Write8(0);
return true;
}
// ARM mode
const uint32_t nopEncoding = hasNOP() ? ARMv6T2_NopEncoding
: ARMv4_NopEncoding;
uint64_t NumNops = Count / 4;
for (uint64_t i = 0; i != NumNops; ++i)
OW->Write32(0xe1a00000);
OW->Write32(nopEncoding);
// FIXME: should this function return false when unable to write exactly
// 'Count' bytes with NOP encodings?
switch (Count % 4) {
default: break; // No leftover bytes to write
case 1: OW->Write8(0); break;
@ -381,8 +402,9 @@ namespace {
class ELFARMAsmBackend : public ARMAsmBackend {
public:
Triple::OSType OSType;
ELFARMAsmBackend(const Target &T, Triple::OSType _OSType)
: ARMAsmBackend(T), OSType(_OSType) { }
ELFARMAsmBackend(const Target &T, const StringRef TT,
Triple::OSType _OSType)
: ARMAsmBackend(T, TT), OSType(_OSType) { }
void ApplyFixup(const MCFixup &Fixup, char *Data, unsigned DataSize,
uint64_t Value) const;
@ -413,8 +435,9 @@ void ELFARMAsmBackend::ApplyFixup(const MCFixup &Fixup, char *Data,
class DarwinARMAsmBackend : public ARMAsmBackend {
public:
const object::mach::CPUSubtypeARM Subtype;
DarwinARMAsmBackend(const Target &T, object::mach::CPUSubtypeARM st)
: ARMAsmBackend(T), Subtype(st) { }
DarwinARMAsmBackend(const Target &T, const StringRef TT,
object::mach::CPUSubtypeARM st)
: ARMAsmBackend(T, TT), Subtype(st) { }
MCObjectWriter *createObjectWriter(raw_ostream &OS) const {
return createARMMachObjectWriter(OS, /*Is64Bit=*/false,
@ -497,18 +520,18 @@ MCAsmBackend *llvm::createARMAsmBackend(const Target &T, StringRef TT) {
if (TheTriple.isOSDarwin()) {
if (TheTriple.getArchName() == "armv4t" ||
TheTriple.getArchName() == "thumbv4t")
return new DarwinARMAsmBackend(T, object::mach::CSARM_V4T);
return new DarwinARMAsmBackend(T, TT, object::mach::CSARM_V4T);
else if (TheTriple.getArchName() == "armv5e" ||
TheTriple.getArchName() == "thumbv5e")
return new DarwinARMAsmBackend(T, object::mach::CSARM_V5TEJ);
return new DarwinARMAsmBackend(T, TT, object::mach::CSARM_V5TEJ);
else if (TheTriple.getArchName() == "armv6" ||
TheTriple.getArchName() == "thumbv6")
return new DarwinARMAsmBackend(T, object::mach::CSARM_V6);
return new DarwinARMAsmBackend(T, object::mach::CSARM_V7);
return new DarwinARMAsmBackend(T, TT, object::mach::CSARM_V6);
return new DarwinARMAsmBackend(T, TT, object::mach::CSARM_V7);
}
if (TheTriple.isOSWindows())
assert(0 && "Windows not supported on ARM");
return new ELFARMAsmBackend(T, Triple(TT).getOS());
return new ELFARMAsmBackend(T, TT, Triple(TT).getOS());
}

10
llvm/test/MC/ARM/nop-armv4-padding.s Normal file
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@ -0,0 +1,10 @@
@ RUN: llvm-mc -triple armv4-apple-darwin %s -filetype=obj -o %t.obj
@ RUN: macho-dump --dump-section-data < %t.obj > %t.dump
@ RUN: FileCheck %s < %t.dump
x:
add r0, r1, r2
.align 4
add r0, r1, r2
@ CHECK: ('_section_data', '020081e0 00001a0e 00001a0e 00001a0e 020081e0')

10
llvm/test/MC/ARM/nop-armv6t2-padding.s Normal file
View File

@ -0,0 +1,10 @@
@ RUN: llvm-mc -triple armv6t2-apple-darwin %s -filetype=obj -o %t.obj
@ RUN: macho-dump --dump-section-data < %t.obj > %t.dump
@ RUN: FileCheck %s < %t.dump
x:
add r0, r1, r2
.align 4
add r0, r1, r2
@ CHECK: ('_section_data', '020081e0 007820e3 007820e3 007820e3 020081e0')

12
llvm/test/MC/ARM/nop-thumb-padding.s Normal file
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@ -0,0 +1,12 @@
@ RUN: llvm-mc -triple armv6-apple-darwin %s -filetype=obj -o %t.obj
@ RUN: macho-dump --dump-section-data < %t.obj > %t.dump
@ RUN: FileCheck %s < %t.dump
.thumb_func x
.code 16
x:
add r0, r1, r2
.align 4
add r0, r1, r2
@ CHECK: ('_section_data', '8818c046 c046c046 c046c046 c046c046 8818')

12
llvm/test/MC/ARM/nop-thumb2-padding.s Normal file
View File

@ -0,0 +1,12 @@
@ RUN: llvm-mc -triple armv7-apple-darwin %s -filetype=obj -o %t.obj
@ RUN: macho-dump --dump-section-data < %t.obj > %t.dump
@ RUN: FileCheck %s < %t.dump
.thumb_func x
.code 16
x:
add r0, r1, r2
.align 4
add r0, r1, r2
@ CHECK: ('_section_data', '881800bf 00bf00bf 00bf00bf 00bf00bf 8818')